In natural gas wells, gas production decreases due to the decline of reservoir pressure. The cause of this loss of gas production is liquid loading that occurs when water and condensate enter the bottom of the well. Foaming agents are frequently used to aid in the unloading of water and condensate accumulated in the wellbore, thereby increasing production from a loaded well. Foaming agents can be applied either by batch treatments or continuous applications via injecting down a capillary string or via the casing/tubing annulus. Foamers function by reducing the surface tension and fluid density in the wellbore.
Foamers are also used in conjunction with a lift gas to enhance oil recovery from oil wells. U.S. Pat. App. No. 2006-0128990 teaches a method of treating a gas well comprising a chloride-free amphoteric surfactant. U.S. Pat. No. 7,122,509 provides a method of preparing a foamer composition having an anionic surfactant and a neutralizing amine. In U.S. Pat. App. No. 2005-0137114, an aqueous foaming composition comprising at least one anionic surfactant, cationic surfactant, and at least one zwitterionic compound is disclosed. PCT Pat. App. Nos. WO 02-092963 and 2007-0079963 disclose a method for recovering oil from a gas-lifted oil well using a lift gas and a foaming surfactant that consists of nonionic surfactants, anionic surfactants, betaines, and siloxanes.
While such foamers represent a significant contribution to the art of unloading fluids in oil and gas wells, there still remains a need for improved foamers and methods of using improved foamers. It is thus an objective of this invention to provide a cost-effective foamer for unloading oil, water, or mixtures thereof from oil and/or gas wells. Such improved foamers would also ideally possess anti-corrosive properties.